Gripper mechanism for printing presses



Feb. 24, 1948. w, DAvlDsON r AL 2,436,765

GRIPPER MECHANISM FOR PRINTING PRESSES Filed Sept. 11, 1944 4 Sheets-Sheet l 'HHUHIUF www 4 sham-sheet 2 Feb. 24, 194s.

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GRIPPER MECHANISM FOR PRINTING PRESSES Filed Sept.'11. 1944 4 Sheets-Sheet 5 sa 6 4 z5 55 2s D A 1 ".v

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passing the chain around the blanket roller of a Patented Feb. 24, 1948 GRIPPER MECHANISM FOR PRINTING PRESSES William Ward Davidson, Evanston, and Nils Trydal and Frank J. Breman, Chicago, Ill., assignors to Davidson Manufacturing Corporation, a corporation of Illinois Application September 11, 1944, Serial No. 553,518

13 Claims. (Cl. 101-232) In printing presses designed for high quality work, it is essential that the registration of the sheets be substantially perfect and when a freshly printed sheet is to be re-run for additional printing, it is essential that the feed and registration be of such character as to avoid smudging the partially dried ink.

In the form of presses with which it is now planned to use the present invention, the sheet to be printed has heretofore been registered againsty preliminary stop fingers and then quickly accelerated by a pair of rollers which gripped it tightly and were driven in timed relationship to feed the sheet against the final stop lingers associated with the gripper. In printing according to the usual practice of allowing ink to redry before it is re-run, this served very satisfactorily. If, however, freshly printed sheets were re-run. for additional printing, as in printing the reverse sides, imprinting or multi-color work, there was sometimes some objectional smudging of the ink which was apparently due to slippage between one of the feed rolls and the sheet, only one of the feed rolls being driven. Although other methods of feed and registration were known which did not use the accelerating feed rolls, they were not readily adaptable to the press in question without danger of losing the essential accuracy of registration.

In the press in question, the gripper and stop finger unit was carried vby a pair of chains. In order to obtain uniformity, it was necessary to use the same gripping and stop finger unit for This was accomplished by two-cylinder press. this roller making two revolutions for each printing and thus permitting the use of a chain length equal to twice the periphery of the cylinder. This permitted the use of the registration gripper to strip the sheet from the cylinder and deliver it and return to the cylinder to receive and register the next sheet. 4This chain delivery is extremely important with the particular press in question because this press is capable of printing by two different methods: the lithographic method printing the underface of the 2 gripping unit was necessarily associated with the blanket cylinder raised complications which, however, are solved by the present invention.

According to this invention, the sheet is registered both laterally and longitudinally at the point where it is nally seized by the grippers. The grippers grip the sheet only at the extreme edge Where there is no danger of smudging and the feed rollers which have apparently sometimes'caused a very slight smudging have been eliminated. They reach out to seize the sheet and pull it down into alignment with the blanket to overcome some difficulties encountered in obtaining accurate registration. The simplicity and uniformity resulting from the use of a single gripping unit carried by chains of appropriate lengths for the use of a single gripping unit have been retained.

The use of a single gripper has contributed to uniformity in an unexpected way. Heretofore, with the chain-carried grippers, it was recognized that uniform seating of the grippers in successive cycles was an advantage, and also the inevitable variability in the relationship of the registration stops to the gripper. There was no particular importance in uniformity of timing of the closing of the stop fingers. According to the present invention, vthe reverse is true. The exact positions of the gripping unit and its parts with respect to the cylinder is not so important as the exact uniformity of timing of the closing of the grippers on successive sheets. It probably would be impossible to obtain really satisfactory registration of successive sheets if more than one p gripper were employed; at least it would be diicult and would require expensive manufacturing care and probably expensive maintenance.

In order to be able to print quite close to the leading edge of the sheet, it is important that the grippers be positioned immediately adjacent the cooperating printing surfaces. This makes it important, both for the purpose of clearance and for the purpose of proper and uniform registration of the sheet that the gripper be alined with the printing surface of the roll on which it 0D- erates. Of course the feed table on which the sheet Vrests before it is seized must be positioned so that this printing surface will make clearance with it` This means that the sheet must not only be seized by the grippers and moved in an end- Wise direction, but it must also in some manner by shifted in a perpendicular direction from the position beyond alinement with the printing surface to the position in alinement with the printing surface. According to the present invention,

this is accomplished by permitting the anvil or relatively stationary gripping jaw to spring out for the seizure of the sheet and then controlling the other gripping jaw first to press the sheet against the anvil jaw `and then to press further and press the sheet and anvil `iaw into the proper position for printing of the sheet. It may be surprising that all of this can be done without interference with the registration, but it should be understood that during all of this time, the gripping unit as a whole is rigidly associated with the cylinder by virtue of the fact that the chain is wrapped around the sprocket associated with the cylinder. Furthermore, a reaction bar is provided for safeguarding against any displacement due to the pressure of the cam on the cam follower controlling the gripper fingers.

Additional objectsl and advantages of the invention will become apparent from the following description and from the drawings in which Fig. 1 is a vertical, longitudinal, sectional view of the form of the invention chosen for illustration, being taken approximately on the line I-I of Fig. 3;

Fig. 2 is a fragmentary detail view showing the lost motion connection between the gripper shaft and its actuator;

Fig. Z-A is a fragmentary detail view showing the sheet stop;

Fig. 3 is a horizontal sectional View taken ap-v proximately on the line 3--3 of Fig. 1;

Fig, 4 is a perspective view of the gripper unit;

Fig. 5 is a fragmentary detail view of one end of the gripper unit y Fig. 6 is, a fragmentary, vertical, sectional View taken approximately on the line 6 6 of Fig. 3;

- Fig. '1 is a fragmentary sectional View taken on the line 'I--l of Fig. 6 and showing the gripper unit as it approaches the printing cylinder;

Figs. 8, 9 and 10 are fragmentary views somewhat similar to that of Fig. 7 but showing the gripper unit in successive positions; and

Figs. 11 to 13 are views showing a modified arrangement for permitting reversal of the press without jamming the gripper mechanism.

Although the law requires a full and exact description of at least one form of the invention such as that which follows, it is of course the purpose of a patent to cover each new inventive concept therein no matter how it may be disguised by variations in form or additions of further iniprovements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements, or combinations in which the inventive concepts are found.

The general organization of the press in connection with which the `present invention is illustrated, is shown in Fig. 1. The press is a twocylinder press having a larger upper cylinder ii and a smaller lower cylinder I2, the latter making two revolutions for one of the bupper cylinder. In offset lithographic printing, the cylinder II bears a lithographie plate along one portion of its periphery and a platen segment along another portion of its periphery and the cylinder I2 bears a blanket I3 (Fig. 9) extending throughout most of its periphery. The plate is rst dampened by a dampening unit indicated diagrammatlcally by the damping roller I4 and then inked by an inking unit indicated diagrammatically by inking ferm roller I6. The plate then transfers the image to the blanket on the cylinder I2 and as the platen segment reaches the cylinder I2, a sheet is fed between the cylinders so that the blanket prints the underface of the sheet. The sheet is then carried around sprocket II to turn the printed face up and is released onto a suitable receptacle or conveyor. In direct-raised image printing, the damping unit represented by I4 is omitted, the platen segment is replaced by a segment bearing raised image printing matter such as type, and this is inked and applied to the sheet as the sheet passes through the bite and the sheet is discharged from the press before being carried around sprocket I1 so Vthat it will again be delivered with the printed face up.

A press of this type is now well known, being that which has been manufactured in recent years by the Davidson Manufacturing Corporation, It is fully described in Davidson Patent No. 2,387,750, dated October 30, 1945. In many fundamental respects, it is similar to the press disclosed in Davidson Patent No. 2,306,044,

The present invention is concerned with the handling of the sheet and hence only the features relating to the handling of the sheet need be described in detail.

General description of sheet handling Successive sheets are separated from a pile by suitable separator mechanism, not shown, and

fed t0 belts I8 in timed relationship with respect to the press cycle, the timing being controlled by a cam on the printing cylinder. The belts I8 are biased to side register the sheet against a side guide I9 along which the sheet is slid until it strikes stop fingers 2i, seen best in Fig. 2-A. If desired. a side logger may be provided for pressing the sheet against the side guide at this time. While the sheet is held in this position, it is snatched by the grippers of gripping unit 22, the stop fingers 2| simultaneously moving ,out of the way. The grippers carry the sheet to the bite between the cylinders and then 'strip the sheet from the printing surface, the

gripping unit being carried by chains 23. The gripping unit is opened at the proper time for delivering the sheet, either before the gripper has passed around the sprocket I'I or afterwards, depending upon which face of the sheet has been printed. The gripper then returns to snatch the next sheet and carry it through the press in the same manner.

Stop finger control IThe stop fingers 2l are carried by a shaft 2t pivoted to the press frame 2t. A crank lever 2i is fast on the shaft 2t and is urged against adjustment screw 28 by spring 29. As the sheet is snatched by the gripping unit, shaft 2d will be pivoted'to shift the grip fingers 2i approximately to the dotted line position. This is accomplished by means of a cam 3l rotating with cylinder1 II which thrusts cam follower lever 32 toward the right about its pivot 33, the thrust being transmitted to lever 2l by a connecting link 34.

The adjustment screw. 28 will usually be set' at the factory to give the desired accuracy in the end registration of the sheet. If necessary, side jogging means may be provided for ensuring accurate registration of the sheet laterally but present indications are that this will not be 'necessary because the sheets seem to be reliably held against the guide bar by the biased -belts I8.

Gripper unit The gripper unit includes a bar or frame 36 which is preferably of angular cross section for rigidity and includes at its ends slots 31 for reby which the gripper unit 22 is carried. This makes a very rigid construction so that when the links bearing lugs 38 are in the portion of the chain which is wrapped around the sprocket rotating rigidly with cylinder I2, the gripper unit itself is rigidly associated with the cylinder. Of course some parts of the gripper unit will move but the gripper unit as a whole, and particularly the bar or frame 3 6 will be rigid with respectr to the cylinder at this time.

The frame 36 includes brackets 4l which may be integrally cast as part of the frame. To these brackets, gripper shaft 42 is journalled. The shaft 42 has secured thereto a plurality of grip ngers 43, and cooperating with each of the nngers 43 is an anvil grip finger fili which is pivotally carried by the shaft 42. As seen best in Fig. 9, the anvil grip fingere@ is urged in a clock- .wise direction by tension spring 46, the movement of the finger in this direction being limited by flange 41 of frame 36.

The shaft 42 is urged in the same direction by spring 4 seen best in Fig. 5. This spring urges the grip ngers i3 toward the dotted line position shown in Fig. 8 in which the grip fingers strike the flange 41. This is the wide-open psition of the gripper.

During most of the cycle, the grip fingers 43 are held in a closed or nearly closed position by cam plate @9 against which cam roller 5l rides, the cam roller l being carried by cam follower lever 52, as best seen in Figs. 2 and 4. As seen best in Fig. 2, the cam follower lever 52 has a shoulder 53 bearing against a peg 541v fast on shaft 52. Thus it isv evident that when the lever 52 is pressed in the right direction by cam plate 59, it will pivot the shaft 42 to close or partially close the grip fingers B3.

Gripper cycle where the cam follower roller 52 may swing freel from cam plate 49 so as to allow the grip iingers 43 to swing all the way open against the flange 41, as seen in dotted lines in Fig. 8. A

cushion could be interposed, or some other silencing stop used, if preferred. The grippers remain in this relative position until the cam follower roller 5l strikes the shoulder 51 of the cam plate 49 at which time the shoulder 51 flips the fingers 43 to the position shown in Fig. 9`in which position the grip fingers 43 are clampingthe sheet 58 against the anvil grip fingers 44. Initially, the grip fingers 43 will be pressed down by operation of the cam plate 49 just far enough to unseat the tail portion 59 of anvil fingers 44 from the ange 41. This unseating is desirable in order to be sure that the gripping pressure is uniform among the various grippers, the uniformity being assured by operation of the springs 46 provided that the tail members 59 are unseated.

It will be observed from Fig. 9 that the sheet 58 being snatched is supported by a table member 6l which must necessarily be positioned radially beyond the blanket I3. For various reasons, however, it is desirable that when the sheet enters the bite, its leading end be held substantially in alinement with the surface of the blanket I3. In other words, the sheet must be seized outwardly of or above the blanket and drawn inwardly or downwardly to the level of the blanket. According to the present invention, this inward or downward movement of the sheet is accomplished very simply by moving the fingers 43 further downwardly, these fingers pressing the anvil fingers 44 downwardly in like manner against the tension of the spring 46. This movement is accomplished through the proper shaping of the cam plate 49, the surface portion 62 thereof being shaped to slightly approach the axis of the cylinder l2.

' The cam plate 49 holds the grippers closed until it is time to release the sheets. The time of release will depend on the position of the cam segment, 53, seen best in Figs. 1 and 3. This cam` segment is shiftably carried by a pair of studs 6d which slide in bushings 66 fast on the cam plate dii. The cam segment 33 is held in either of the adjusted positions by set screw 6l. The position of cam plate 63 shown in Fig. 3 is an inactive position in which i't does not engage the cam follower roller 5l. Instead the cam follower roller 5l follows the receding portion 68 of cam plate 49, thus allowing the ngers 43 to open enough to release the sheet so that it will be ejected from the press at this point. Election rollers may be provided if desired.

If the cam plate 63 has been shifted to a position adjacent to or engaging the cam plate 49, the gripper will not open at this point as the fingers will be restrained from opening by coaction between the roller 5l and cam plate 53, Thus the sheet will be carried around guide wheels 69 to be turned over. It will be understood that this turn-over will be provided only when the underface of the sheet has been printed. In this case, the sheet will be released when the roller 5l moves along the receding surface 1l, this receding surface being similar to surface 49 and permitting the grip fingers 43 to spring open far enough to release the sheet, thus completing the cycle of the gripper unit. This receding surface 1i may be directly on the cam plate 49 in which case it will be invariably in position or it may be formed on a sliding plate 12 adjustably carried by the cam plate 49. It should be noted incidentally that a sheet stop is preferably provided to stop the sheet and cause it to drop down as it is released and this stop should also be adjustable so that it may stop the sheet whenever it is released by the cam surface 1|. There is noneed at this point for a cam plate similar to the cam plate 63 and arranged to be shiftable to and from active position because even if the sheet has pre- Viously been released, there is no harm in .opening the grippers at this point again.

In short, it is seen that the grip lingers 43 open wide to pass under and beyond the waiting sheet, thus allowing the anvil lingers to spring out to the right' position to engage the sheet without ensayos that it is seized until the time that it enters the bite except that accurately predetermined shifting resulting from the pivotal movement of the grip fingers. Since a single gripping unit is used, there is no chance for variations in this regard between successive gripping units and hence extremely accurate registration is bound to result. It may also be observed that the gripping unit is positioned at least reasonably accurately for successive sheets since there is a single gripping unit carried by links which could be expected to engage the sprocket in the same way each time. Even if there should be slight variations in this position between successive cycles, there would be no loss of accuracy o! registration so long as the gripper remained registrationally rigid with the cylinder from the time it seized the sheet until the sheet entered the bite. The term registrationally rigid" might be taken as excluding any circumferential creep of the chain on the sprocket or any other movement that would destroy registration.

Beyond the bite, the gripping unit is drawn away from the cylinder by the chains, thus stripping the sheet from the cylinder and at the proper time, either before or afterI turning the sheet over, depending on which face of the sheet was printed, the grip ngers will release the sheet to discharge it from the press.

Reaction bar The pressure of the cam plate 49 on cam roller l will exert a torque on gripper frame 39 which might tendto twist this frame out of its natural position, thus either permitting the grippers to open slighly or causing some erratic seating of the chain on thev sprocket 39. Such erratic seating must of course be avoided because it might result in some shifting of the gripping unit with respect to the cylinder between seizing the sheet and carrying it to the bite and such shifting would destroy the accuracy of the registration. Accordingly, reaction bar 13 is provided being carried Reversz'bility Although the press will normally be operated only in one direction during printing, it will sometimes be turned backwards at least a little for making various adjustments and the like. If we assume, however, that it will be stopped at the position shown in Fig. 8 with the gripper parts shown in their dotted position, it will be apparent that turning the press backwards could have an undesirable effect. As the cam follower 5I moving backwards strikes the cam plate 49, it will be turned in a clockwise direction with respect to the shaft 42 by which it is carried. The shaft 62, however, cannot pivot further in this direction since `it is restrained by virtue ofthe fact that the grip fingers 43 fast on the shaft 42 are resting against iiange 41. Lost motion, is, therefore, provided in order to permit the further clockwise movement of roller 5I about shaft 42. This lost motion is `seen best in Fig. 2.

The arm 52 is loose on shaft 42. As previously mentioned, the 'shoulder 53 normally bears on peg 54. When the press is turned in reverse direction, however, the shoulder 5 3 may depart from the peg 54 inorder to permit the lever 52 to swing clockwise from the dotted line position d seen in Fig. 3. Spring 'i8 tends to hold the shoulder 53 in contact with the peg 54 so that the lever 52 will return to its normal position as soon as it is released by the cam plate 49.

Although the illustrated structure works entirely satisfactory initially, it is possible that some undesired play will result due to long usage. This danger can be avoided by elongating the sleeve 19, perhaps extending it all the way into the enlarged portion of shaft d2. It may also be desirable to provide something more sturdy than the shoulder 59 and peg 54. For example, the engagement member corresponding to the member '54 could be a specially shaped collar fitted on a squared portion o the shaft d2 between lever 52 and the roller 1d.

There is one condition which is not adequately cared for by this lost motion connection. When the parts are approximately in the position shown in full lines in Fig. 3 and just before the lever 52 has snapped free of cam 49, the parts are in a position that might be called a dead center position because the roller 5i will not roll back along the cam if the parts are turned backwards. To overcome this difficulty, it is necessary to have some yieldability so that the lever d2 can pass the dead center position as the press is turned backwards. As seen in Fig. l, this can be provided by using a resiliently mounted section 8l of cam t9. This segment may be pivoted to one of the studs d2 supporting the cam plate 69 and may be urged against stud 89 by a spring B4. The spring 94 may be stii enough not to yield during ordinary operation of the press so long as it yields when the apparatus is turned backwards from the Fig. 8 position.

Of, course any other form of resiliency could be provided. It is even possible that it the cam receded steeply just to the right of the sloping portion 12 thereof in Fig. 1, so as to let the arm 52 snap free at that point, that suflicient resiliency would be provided by the chain to accommodate the dead center condition since the dead center condition would then be occurring when the links carrying the gripper unit were not seated on the sprocket.

Another arrangement for permitting reversal of the press is shown in Figs. 11 to 13 and is at present preferred. It will be noted that these figures show a modied cam arrangement in which the front portion of the cam is omitted .and in which the cam may be built up from a Y plurality of smaller plates 49' with their ends abutting together. In Fig. 11 the dotted line 50 represents a bracket on the press frame on the near side of the cam 49'. It may have a flange extending partially over the cam for bracing the separate plates 49 which are carried by the bracket. f t

In Figs. 11 to 13 the gripper shaft 42 is actuated by a broken lever comprising the members 9i and 92, the follower roller 5I being carried by the member 92, which is pivoted to the member 9|, this latter being fast on shaft 42. The member or lever 92 is provided with a stop lug 93 whichbears against the arm 9| to limit the movement of lever 92 in a clockwise direction about its pivotal point; hence when the follower roller 5I strikes cam face 51, the levers 9| and 92 will act together as a rigid lever to turn shaft 42. The lever 92 is normally held with its stop 93 in engagement with arm 9| by means of a spring 94 seen best in Fig. 13.

If the press should be turned backwards t0- wards the position shown in Fig. 12, the follower 9 roller would strike the curved portion I8' of lower cam plate 49' and the broken lever comprising arms 9| and 92 would then be bent at'the elbow as clearly seen in Fig. 12. The parts should be so proportioned that the roller 6i may be pressed inwardly as far as necessary-to clear even the highest part of the cam 49'. As the parts have been shown in this application, this necessitates shifting the roller 5l so i'ar that its axis is closer to the axis of cylinder Il than is the axis of shaft 42. This movement is made possible now, even when the lever 9i is in its outer position corresponding to the wide open position of the grip fingers by making the lever 92 longer than the arm 9i.

Although the press will only occasionally be turned backward, and then usually only for a fraction of a revolution, it is important to have adequate bearings for the broken lever comprising members ai, y92 and 52. Even though there is not much Wear, a dependable positioning of the parts is important in obtaining uniform registration. This is accomplished as seen best in Fig. 13. The roller 5i is provided with a reasonably long bearing on a pin 96 which is rigid with lever 92. Lever '92 is rigid with pin 97 which has a long bearing engagement with arm 9i by virtue of having a boss 98 formed on arm 9i. The arm 9i is fast on the shaft t2. In this construction reaction roller i4 is positioned inwardly of the arm 9i, as illustrated, and it may be provided with rolling or other suitable friction reducing bearings.

From the foregoing, it is seen that an extremely satisfactory feed and delivery structure has been i provided. The sheet is registered right at the position where it is seized by the final grippers so that there is no danger of even the slightest departure from registration in moving from the registered position to a position Where it would be seized. There are no accelerating rollers which are likely to mar a freshly printed sheet being resrun for occasional printing. The gripper unit as a whole is rigidly associated with the printing cylinder from the time this sheet is seized until the sheet enters the bite so that there is no danger of loss of registration by shifting of the unit during this interval. A single gripping unit is used for all sheets so that there is no danger of loss of registration due to differential registration between gripping units. In spite of the fact that both sets of gripping members reach out to take a sheet from the feed table above the cylinder, they draw the sheet into the cylinder before the sheet reaches the bite. In other words, the gripper faces are at the time of gripping alined with the sheeton the feed table whereas at the time the sheet enters the bite, the gripper faces are approximately alined with the surface of the blanket. As a matter of fact, with proper shaping of the cam surface 62, the faces of the grippers will stay approximately alined with the portion of the sheet just beyond the grippers at all times so there will be no tendency to crease the sheet. This is especially desirable when the grippers are quite close to the feed table 6I, it being noted that the feed table is notched as seen in Fig. 3 so as to permit the grippers to grip the sheet While its gripped edge is still accurately positioned on the table, notches also being provided to receive the stop fingers 2 I. There is no danger of a sheets being nicked since it is neither jammed forcefully against inadequate stop surstationary registered position adjacent the pathA of the gripper unit. and cam means controlling the gripper unit to cause it to seize a sheet from said position and hold it in registered position With respect to the cylinder until the sheet is seized by the printing couple, the gripper unit as a Whole being rigidly associated with the cylinder from the time it seizes the sheet until the sheet is seized by the couple, the portion of the endless means by which the gripper unit is carried being in wrapped engagement with meansA rigid witl. the cylinder throughout said time, and reaction means for absorbing the reaction of thecam means and restricting its movement in at least one direction to guard against displacement of the gripper unit as a result thereof.

2. A gripper unit for printing presses and the like including a pivotally mounted shaft biased in a given angular direction, anvil means pivotal-1 ly mounted on the shaft and biased in the same angular direction, grip finger means fast on the shaft, means limiting the biased movement of the anvil means so that the biased movement of the grip fingers opens the grippers, and control means for pivoting the shaft in the opposite direction to close the grip finger means upon the anvil means.

3. A gripper unit for printing presses and the like including a pivotally mounted shaft, anvil means pivotally mounted on the shaft and biased Vin a given angular direction by spring means,

i means limiting the biased movement of the anvil means, grip finger means fast on the'shaft, additional spring means for moving the shaft in said direction to open the gripper unit, and cam means to move the shaft in the opposite direction to close the grip nger means upon the anvil means.

4. A gripper unit for printing presses and the like including a pivotally mounted shaft biased in a. given angular direction, anvil means pivotally mounted on the shaft and biased in the same angular direction. grip linger means fast on the shaft, means limiting the biased movement of the anvil means so that the biased movement of the grip fingers opens the grippers, and control means for pivoting the shaft in the opposite direction to close the grip finger means upon the anvil means, and to pivot the anvil means in the opposite direction while retaining a gripping pressure thereagainst.

5. A gripper unit for printing presses and the like including a pivotally mounted shaft, main gripper means fast on the shaft and having a plurality of Sheetngaging faces, a plurality of separate anvil members each pivotally mounted on press the anvil members away from their moveiii `means for operating the control lever, said cam means being so constructed as to'permit the control lever to move so close to a radial or dead center position that if the cylinder were turned backwards the control lever would jam against the cam if the parts were rigid, said control lever having a pivoted connection therein permitting it to collapse upon backwards motion of the cylfinder, and means limiting the p-ivotal movement of the pivotal connection with the opposite direction so that during forward movement of the cylinder the lever will function as a rigid lever.

"i, A gripper unit for printing presses and the like comprising a frame, a spring loaded shaft pivotally mounted in said frame and normally biased in one direction, spring loaded anvil means carried in said frame and normally biased in the saine direction as said shaft, grip nger means fixed to said shaft and in the said one position of the latter being disposed away from said anvil means, and control means associated with said shaft for pivoting the latter in a direction opposite said one direction thereof to move said grip finger means towards said anvil means.

8. A gripper unit for printing presses and the like comprising a frame, a spring loaded shaft pivotally mounted in said frame and normally biased in one direction, spring loaded anvil means carried in said frame and normally biased in the same direction as said shaft, grip finger means aecomo fixed to said shaft and in the said one position thereofA being disposed away from said anvil means, and control means associated with said shaft for pivoting the latter in a direction opposite said one direction thereof to engage said grip finger means with said anvil means, said control means upon engagement of said grip nger means with said anvil means being adapted to pivot said grip finger means and said anvil means in a direction opposite the direction in which the latter is normally biased.

9. A gripper unit for printing presses and the like comprising a frame, a shaft pivotally mounted in said frame, spring means associated with said shaft for normally biasing the latter ln one direction, anvil means pivotally mounted on the shaft, spring means between said anvil means and said frame for normally biasing said anvil means in the same direction as said shaft, grip finger means fixed to said shaft and in the normal position. of the latter being disposed away from said anvil means, and contro1 means associated with said shaft for pivoting the latter against the force of the spring means associated therewith to move spring means between said anvil means and said frame for normally biasing said anvil means in the same direction as said shaft, grip finger means fixed to said shaft and in the normal position of the latter being disposed away from said anvil means, and control means associated with said shaft for pivoting the latter against the force of the spring means associated therewith to move said grip finger means toward said anvil means, said control means upon engagement of said grip finger means with said anvil means being adapted to pivot said grip finger means and said anvil means in a direction opposite the direction in which the latter is normally biased.

ll. For use in a printing press having a pair of printing cylinders forming a bite therebetween, a gripper unit movable with one of said cylinders comprising a frame, a spring loaded shaft pivotally mounted in said frame and nor mally biased in one direction, spring loaded anvil means having a sheet engaging portion carried in said frame and normally biased in the same direction as said shaft to a position in which said sheet engaging portion is adapted to project beyond the periphery of said one cylinder, grip finger means lxed to said shaft and in the said one position thereof being disposed away from said anvil means, and control means associated with said shaft for pivoting the latter in a direction opposite said one direction thereof to move said grip finger means into engagement with said anvil means, said control means upon engagement of said grip finger means with said anvil means being adapted to pivot said grip finger means and said anvil means in a direction opposite the direction in which the latteris normally biased to dispose said sheet engaging portion of said anvil means Within the periphery 0f said one cylinder,

12. In combination a printing press having a printing cylinder, flexible endless means extending around said cylinder and away therefrom, a gripper unit carried by said endless means and at times coacting with said cylinder, said gripper unit comprising a spring loaded shaft normally biased in one direction, spring loaded anvil means having a sheet engaging portion normally biased in the same direction as said shaft to a position in which said sheet engaging portion is adapted to project beyond the periphery of said one cyllnder, grip finger means carried by said shaft and normally disposed in a position away fromsaid anvil means, and control means comprising a cam follower associated with said shaft and a. cam plate disposed about the path of said endless track means with which said cam 'follower has engagement, said control means being operative at a predetermined position of engagement of said cam follower with said cam plate to pivot said shaft in a direction opposite said one direction thereof to engage said' grip finger means with said anvil means, said control means being adapted upon 'engagement of said grip finger means with said anvil means to pivot said grip finger means and said anvil means in a direction opposite the direction which the latter is normally biased to dispose said sheet engaging portion within the periphery of said cylinder, and said control means in other predetermined positions of engagement of said cam follower with said cam plate providing for separation of said grip finger means from said anvil means by movement of said shaft toward its normally biased position.

13. Sheet gripping mechanism for use in con- 13 `iunction with a' rotary printing member adapted to receive sheets from an adjacent feed table. said mechanism includinl trip ilns'ers biased to an open position adapted to pass said table, and means for closing the :ripper nzers on a sheet on said table including a control arm and a stationary shoulder struck by the control arm, said control arm comprising two portions pivoted together and means limiting their movement in the direction they would pivot when striking their shoulder whereby they will act as a rigid arm in closing the gripper lingers, the construction of the pivotal connection permitting the levers to collapse to a position such that when the rotary ymember is turned in reverse direction the con- 1 trol arm can pass under such shoulder.

WILLIAM WARD DAVIDSON. NILB TRYDAL. FRANK J. BREMAN.

REFERENCES crrnn The following references are of record in the le of this patent:

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